Telecommunications – Radiotelephone system – Auxiliary data signaling
Reexamination Certificate
1999-01-22
2002-12-24
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Auxiliary data signaling
C714S746000, C714S786000, C370S337000
Reexamination Certificate
active
06498936
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods and systems for radio communications, and more particularly to methods and systems for wirelessly broadcasting messages to wireless terminals such as radiotelephones.
BACKGROUND OF THE INVENTION
Commercial radio communications are widely used for voice and/or data communications. Pagers and cellular phones, in particular, have become relatively common. These two different types of communication devices, and supporting systems, have evolved from different fundamental purposes. In particular, pagers traditionally provide one-way, limited information to one or more end users and cellular phones traditionally provide two-way voice communication service.
As time and technology progress, the traditional functional dividing lines between these two different types of radio communication devices have become blurred. Pagers have acquired some of the functionality that was traditionally provided by cellular phones and vice-versa. For example, two-way pagers have been developed which permit the pager user to transmit messages to the paging system, which messages can then be forwarded to other parties. Similarly, cellular phones have acquired the capability to transmit and receive short (e.g., on the order of 160 alphanumeric character) text messages which can be output on the display of a cellular phone.
This evolution in radio communication devices has led to the development and marketing of a host of new information services. For example, paging systems have been implemented which provide for the broadcast of information services, e.g., stock quote information services, to a large number of subscribers that have pagers with displays. These pagers periodically receive information over an air interface associated with a large number of stocks or other financial instruments such as options, futures. etc., and display the current prices of these instruments so that a user can track a portfolio's performance.
Users of cellular phones may have interest in the provision of a similar service which would provide information service support in a cellular network. However, cellular systems, unlike paging systems, have conventionally been designed around the paradigms of (1) limited bandwidth due to a restriction on the spectrum allocated by various governing bodies such as the FCC for cellular applications and (2) the notion that most of the limited bandwidth should be reserved for point-to-point connections such as voice connection between the cellular phones and the system, with only a relatively small fraction being reserved for broadcast (point-to-multipoint) transmissions from the system to the cellular phones operating in the system. Due to this latter feature of cellular systems in particular, system designers generally are very careful regarding the amount of information transmitted on the available broadcast channels and the frequency with which this information is repeated. Thus, the provision of broadcast information services to cellular radio communication systems may not readily be accomplished by the most straightforward approach of broadcasting whatever information is desired for all subscribers to display on their cellular phones.
For example, in a Time Division Multiple Access (TDMA) cellular radiotelephone system, each radio frequency is divided into a series of time slots, each of which contains a burst of information from a data source, e.g., a digitally encoded portion of a voice conversation. By time multiplexing bursts associated with different sources, more than one channel can be supported on each radio frequency. The time slots are grouped into successive TDMA frames having a predetermined duration. The number of time slots in each TDMA frame is related to the number of different users that can simultaneously share the radio channel. If each slot in a T DMA frame is assigned to a different user, the duration of a TDMA frame is the minimum amount of time between successive time slots assigned to the same user.
The successive time slots assigned to the same user, which are usually not consecutive time slots on the radio carrier, constitute the user's Digital Traffic Channel (DTC). As mentioned above, this is typically a point-to-point resource. In fact, TDMA systems generally reserve the majority of the available radio channels for use as DTCs to ensure a large traffic capacity. However, as described in more detail below, Digital Control CHannels (DCCHs) are also provided for communicating control signals and overhead information, including a mechanism for connecting to the radio communication system and being assigned a DTC.
Similar types of resource allocations are found in other types of cellular systems. For example, in Code Division Multiple Access (CDMA) systems, channelization is performed by spreading data associated with a particular connection using a unique spreading code. This code, as opposed to or in conjunction with frequency and time differentiators, provides the receiver with a mechanism for extracting its intended data, by correlating the received composite signal with the code assigned to its traffic channel. Like TDMA systems, CDMA systems can also provide for broadcast control channels or other overhead signaling channels by allocating known codes thereto. However, like TDMA systems, CDMA systems also tend to reserve more resources, such as codes and power, for dedicated traffic channels than for broadcast information channels. Accordingly, it would be desirable to provide methods and systems which are able to provide broadcast information services within the constraints of existing cellular radio communication systems. In particular, it would be desirable to design broadcast information methods and systems that can accommodate an end user's desire for a relatively large quantity of data that may need to be updated relatively frequently, while reducing and preferably minimizing the usage of scarce broadcast channel resources.
GSM systems presently can offer broadcast services. ANSI 136 has defined a broadcast channel that provides enhanced flexibility with respect to bandwidth allocation, sub-channelization, content description and change notification. However, broadcast services may not be extensively used in the future for the ANSI 136 or ANSI 95 technologies.
Packet data communication, a point-to-point form of communication, may provide access to the same services. Packet data communication, using for example GPRS as will be the supported in both GSM and ANSI 136, are being elaborated in the standards setting groups and resources are being assigned to the development of such products by vendors. Thus, the user may use a packet data service to access an Internet-based stock quote service in which the user's portfolio is downloaded to a wireless terminal upon request by the user. Using a broadcast service, all the securities, possibly limited to a subset of all available securities in interest of bandwidth limitation, are sent on a broadcast channel. The wireless terminal continually or as a result of a user request reads the entire set of securities on the broadcast channel and further manipulation of the data. For example, extraction of the data for presentation as defined by the specific user's portfolio may take place in the mobile station or in a companion lap-top computer.
Wireless packet data systems are now being developed and being made available. This is amplified by the ITU initiated development of “3:e generation” wireless systems. A focus of this activity is to provide a packet data services as efficiently as possible with bit-rates of 144 kbit/s, 384 kbit/s and 2 Mbit/s depending on the environment. To provide wireless packet data, the operators may only need to obtain the necessary equipment and then the user can access the Internet or a corporate mail system. However, the operator may then only provide a wireless bit-pipe but no content. The content provider may be the same companies that provides content in the wireline environment. A current trend in th
Cong Le Thanh
Corsaro Nick
Ericsson Inc.
Myers Bigel & Sibley & Sajovec
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